R help - Apr 2012 - Deleting observations from baseline that don't appear in follow up

Hello all,
I'm almost embarrassed to post this , it seems so easy.  Suppose I have a
baseline and follow up survey but some people are missing in the follow up:
> baseline<-data.frame(id=c(3,5,7,9,12), data= runif(5))
> follow.up<-data.frame(id=c(3,7,9,12), data= runif(4))
> baseline
  id       data
1  3 0.66771988
2  5 0.28794744
3  7 0.01892821
4  9 0.64863175
5 12 0.86485882
> follow.up
  id      data
1  3 0.8237210
2  7 0.8140544
3  9 0.8803674
4 12 0.8031520

Here, in follow up we are missing person #5.  I need to delete him from the
baseline, so that I have an equal number of rows once again.  Obviously

baseline<-baseline[-2,] won't cut it here, since in my data set I have
thousands of people.

Thanks in advance

Justin

	[[alternative HTML version deleted]]

What about

baseline[baseline$id %in% follow.up$id, ]

or the same thing but using subset().

Sarah

On Fri, Apr 27, 2012 at 4:36 PM, justin jarvis
<littledude.jarvis at gmail.com> wrote:
> Hello all,
> I'm almost embarrassed to post this , it seems so easy. ?Suppose I have
a
> baseline and follow up survey but some people are missing in the follow up:
>
>> baseline<-data.frame(id=c(3,5,7,9,12), data= runif(5))
>> follow.up<-data.frame(id=c(3,7,9,12), data= runif(4))
>> baseline
> ?id ? ? ? data
> 1 3 0.66771988
> 2 ?5 0.28794744
> 3 ?7 0.01892821
> 4 ?9 0.64863175
> 5 12 0.86485882
>> follow.up
> ?id ? ? ?data
> 1 ?3 0.8237210
> 2 7 0.8140544
> 3 ?9 0.8803674
> 4 12 0.8031520
>
> Here, in follow up we are missing person #5. ?I need to delete him from the
> baseline, so that I have an equal number of rows once again. ?Obviously
>
> baseline<-baseline[-2,] won't cut it here, since in my data set I
have
> thousands of people.
>
> Thanks in advance
>
> Justin
-- 
Sarah Goslee
http://www.functionaldiversity.org

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justin jarvis <littledude.jarvis at gmail.com> wrote:
>Hello all,
>I'm almost embarrassed to post this , it seems so easy.  Suppose I have
>a
>baseline and follow up survey but some people are missing in the follow
>up:
>
>> baseline<-data.frame(id=c(3,5,7,9,12), data= runif(5))
>> follow.up<-data.frame(id=c(3,7,9,12), data= runif(4))
>> baseline
>  id       data
>1  3 0.66771988
>2  5 0.28794744
>3  7 0.01892821
>4  9 0.64863175
>5 12 0.86485882
>> follow.up
>  id      data
>1  3 0.8237210
>2  7 0.8140544
>3  9 0.8803674
>4 12 0.8031520
>
>Here, in follow up we are missing person #5.  I need to delete him from
>the
>baseline, so that I have an equal number of rows once again.  Obviously
>
>baseline<-baseline[-2,] won't cut it here, since in my data set I
have
>thousands of people.
>
>Thanks in advance
>
>Justin
>
>	[[alternative HTML version deleted]]
>
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